U.S. Pat. No. 5,092,496 discloses a dispenser for flowable materials in a barrel. A piston having a flexible sealing rim is telescoped in the barrel. The sealing rim operates in a manner whereby as the barrel is moved downwardly on the piston the pressure from the material in the barrel causes the sealing rim to pivot so as to create sealing surface contact between the sealing rim and the inner surface of the barrel thereby assuring that material will not leak past the sealing rim.
It would be desirable if a dispenser of the type disclosed in U.S. Pat. No. 5,092,496 could be used which would permit reuse of the piston and replacement of simply the barrel with its contents when the contents have been completely expelled from the barrel.